Tuesday, February 07, 2006


Darwin Day at Duquesne University -- The Cambrian Explosion

Derek Briggs, a graduate of Trinity College, Dublin and the University of Cambridge, Director of the Yale Institute for Biospheric Studies, a professor in the Department of Geology and Geophysics, and curator in charge of Invertebrate Paleontology at the Peabody Museum will speak Friday, Feb. 10 at 7:00 pm in Pappert Lecture Hall in the Bayer Learning Center on "The Cambrian explosion - the evidence of the fossil record."

Here's the abstract for Dr. Briggs' lecture:

The fossils of the Cambrian include the earliest examples of most of the major groups of modern animals, from arthropods to vertebrates, and therefore provide critical evidence of the timing and nature of the early evolution of metazoans (many-celled animals) – the Cambrian explosion.

While the fossil record is dominated by hard parts (mineralized shells, bones and teeth) Cambrian rocks yield an unusually high number of deposits that also preserve soft-bodied animals, representatives of those groups like worms that are normally lost through decay but which nonetheless form the major portion of marine communities.

Most famous of these sites of exceptional preservation are the Lower Cambrian localities around Chengjiang in Yunnan Province in China (525 mya), and the Middle Cambrian Burgess Shale of British Columbia (510 mya).

The preceding Ediacaran Period, which dates from 630 mya to the base of the Cambrian at 542 mya, yields a range of remarkable forms known as vendobionts as well as other unusual organisms which are early representatives of lineages leading to the modern groups. The Ediacaran Period is also yielding an increasing number of remarkably preserved embryos, particularly from the 570 my old Duoshantou Formation of China, evidence of how early animals developed.

Briggs' lecture will describe recent discoveries of Cambrian fossils and explain their significance. It will explain how animals become preserved in the rocks and how the evidence of the fossils of the Ediacaran and the Cambrian Periods can be analysed to reveal the nature of the Cambrian explosion.


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